Intel 386 - Manual (Page 620)

D-55
SYSTEM REGISTER QUICK REFERENCE
D.54 RFSCIR
D.55 RFSCON
Refresh Clock Interval
RFSCIR
(read/write) Expanded Addr:
ISA Addr:
Reset State: F4A2H
—
0000H
15 8
— — — — — — RC9 RC8
7 0
RC7 RC6 RC5 RC4 RC3 RC2 RC1 RC0
Bit
Number
Bit
Mnemonic
Function
15–10 — Reserved. These bits are undefined; for compatibility with future devices,
do not modify these bits.
9–0 RC9:0 Refresh Counter Value:
Write the counter value to these ten bits. The interval counter counts
down from this value. When the interval counter reaches one, the control
unit initiates a refresh request (provided it does not have a request
pending). The counter value is a function of DRAM specifications and
processor frequency (see the equation above).
Refresh Control
RFSCON
(read/write) Expanded Addr:
ISA Addr:
Reset State: F4A4H
—
0000H
15 8
REN — — — — — CV9 CV8
7 0
CV7 CV6 CV5 CV4 CV3 CV2 CV1 CV0
Bit
Number
Bit
Mnemonic
Function
15 REN Refresh Control Unit Enable:
This bit enables or disables the refresh control unit.
0 = Disables refresh control unit
1 = Enables refresh control unit
14–10 — Reserved. These bits are undefined; for compatibility with future devices,
do not modify these bits.
9–0 CV9:0 Counter Value:
These read-only bits represent the current value of the interval counter.
Write operations to these bits have no effect.